UPDATED Nov 2011: I found a better way to do this that is posted here

Up until now, I have run my laptop at work with the lid closed and everything on an external monitor on my desk. However, I was starting to get really concerned about the heat (60C idle and 95C under load) and how the little fan was struggling to keep up.

So, I started looking around for tips about how to leave the lid open, but trick my MacBook into thinking the lid was closed and leave the LCD off. I found a few good tips, but I still had to hunt with a magnet for that magical switch point. Well, I found it and the picture is below. Things look pretty frosty so far, let’s hope this extends the life of my 3 year old laptop a bit more.